1. Field of the Invention
The present invention relates to an electrode structure, and more particularly to an electrode structure appropriate for a front board of a plasma display panel (PDP) and fabrication method thereof.
2. Description of the Related Art
PDPs are generally divided into alternating current (AC) and direct current (DC) types. The AC type PDP comprises a front board and a back board. Bus electrodes are formed on the front board. Data electrodes are formed on the back board. The front and back boards are typically glass substrates. The bus electrodes are composed of photosensitive electrode material.
In order to increase the shading values of pixels, the bus electrodes utilize two coats of a screen printing material. As shown in FIG. 1a, a dark color electrode material covers a front board 1 to form a dark color layer 3 and a light color electrode material covers the dark color layer 3 to form a light color layer 5.
The dark color electrode material is ruthenium and the light color electrode material is silver. The electrode material of the dark color layer 3 and the light color layer 5 is different such that shrinkage of the dark color layer 3 and light color layer 5 is not the same. As shown in FIG. 1b, if the shrinkage of the dark color electrode material is more than the light color electrode material, edges of the front board 1 with curl.
In order to solve the uneven shrinkage problem, a conventional method is used to control areas of the dark color layer 3 and the light color layer 5. FIG. 2a shows a conventional front board. A dark color layer 4 is formed on a front board 2 and a light color layer 6 is formed on the dark color layer 4. The area of the light color layer 6 is greater than the area of the dark color layer 4. When a scraper of a screen printing tool contacts the light color layer 6 moving from left to right, a hole 8 is generated in a left terminal of the dark color layer 4, as shown in FIG. 2b. 
FIG. 2c shows a top view of a conventional front board. An electrode pattern comprising electrodes X1˜Xn is formed in the front board. When the hole 8 appears in the electrode X1, the electrode X1 is cut off and malfunctions resulting in reduced PDP yield of the PDP to reduce.